Method of gear generation and apparatus for performing such method



Patented June'28, 1938 i A Y2,121,846Y

PATENT v.o1-1Fici:

'METHOD QF GEAR GENERATION YAPPARIL'IS vrFOR PERFORMING 'SUCH METHOD l iEverard Stubbs', Springfield, -Vt., assigner .to The .FellowsGearShaperCompany, Springfield, Wt, a corporationof Vermont Y Application JuneV26, 1935, serarNo; 128,435

20 HClaims.-

Thepresent invention :relates "to the generation of i gears Vby relative`-reciprocation between the I work-'piece,f(agear blank) land'cutters ofthefgear Shaper type, in the direction of the axes ofthe ciitters,`together with `relative rotation between such cutters jand lthe work`piece lrin the lmanner ofintermeshing'gears; The cutters hereinreferre-d'to as of the Lgear shaper rtyperhave 4teeth arrangedsimilarlytothe-teeth of a gearcon- Y ro* jugateito the teeth to be cutin the ffwork, ybut differing Afrom gearjteeth infthat vthey lhaveycutting edges atene end andvtheirside `iaces'areinclined --convergentlyaway from the Vcutting-'endV to `provide iside clearance-'in the cuttingyaction. y

The-object of thisinventionis to effect rapid generation of Vgears;and-to-dofthiswth a most compact assemblage -of cutter *andAworkspindles and with .cutters :of AAthe `dimensions, and 'other itsen'tirepitch circle. Either completegears'or Y gear segments maybe .madenby thiswmethod. The principlejis thej samein either case. -Between suchcutters and the work are effected relative movements of reciprocatlon inthe'direction yof thecutter axes and relative movements of rota- Vtionabout their respective axes in theinanner of .conjugate gearsv runningin `mesh `with one another; and suchrotational movements may -beimparted .to both the cutters andthe'work piece simultaneously; orztothe cutters onlycompo-unded `of rotation about their ownaxesandrevolu-4tion -fabout the axis 4of the work, in Vthe manner ofjplanet pinons. e

' `Mechanismsr *for 'effecting these movements,

and *for leffecting relief -between the cutter teeth and the Awork tolavoid rub on lthe unoncuttingY Y (return) strokes-have'beendeveloped'as part of an organized machine 4rfor practising this method.Such "machinevand mechanisms, however, beyond .the generic lformulationof means hereinafter referred -to, are -not lof `my invention. What vIhave invented is theemethod of, and theprinciples '.offfmeans "for,acting on a single-work piece by-a i pluralityof L cutterssimultaneously.' with genera- VVtionibyfeach cutter o'faa fractiononly-ofthe whole number of teeth tobe-cut andthe correlation-"of thekcuttersewith one another -so that :their joint eioirt produces acomplete series olf equally spaced teeth. VThis principle maybecombined; and-is so shown in `th'e'present illustration, with two orymore Aseries of teeth or cutting units,of

which the `second set, and the'ffollowing sets if more than twoAareprovided,are'designed toifcut Y deeper an-d/or wider spacesthan'those out by'A the precedingv series; the cutters being solucorrelated.'`

that" a `subsequent -seriesri of teethxon each-'cutter enlarges'thespaces'cut 'by the primary, or other preceding, tooth-seriesof thepreceding cutter.

lof

'The Adrawing furnished herewith :illustratesiin a'diagrammatic mannerithe stepsand operations i-n which this method is comprised,andithefprinciples of a'machineifor performingthe method. -In 4thisdrawing,-

commencement of the `'cutting cycle; Y `Fig. I2lis;asimilarfviewbutshowing-:the cutters and work after `the A'cycle `has Vbeen completed;

Fig. 3 `is adiag-rammatic view showinglin'section the principles ofVmechanisrnssutable V-ior giving reciprocating and -planetaryr'movements to such cutters -relatively-to a 'stationary-work piece.

Referring to Figs 1and"2 ,the\work` piece, a gear blank; is "designateda., and the fcutters nare all designated 11), "but aredistinguished'from one another Vby exponents |'2, 3,'-et-c. Thera-reallA alike; and'eachis provided'wlthfteeth throughout Yonly-afraction-ofitscircumference. y The characteristics of such teeth, as tocutting edges'and side clearance, correspond Asubstantially vtothosesetforthin the Fellows Patent 676,226,` vJ une 11, 1901. -fIn otherword-sthe cutters are ofthe well knownfgear -shaper cutter'- type. y

`v4In Ithis illustration each -cutter has two series ofteeth designatedrespectivelyt andt'owhich, those vof the first series constitute v'oneYcutting Vunit andare designed *to -generate spaces or grooves in A'the-work -of less Mwidth `and depth than `the prescribed final dimensions,lwhile the teeth t2, longer-and'widenthan Ythe :teeth t-con stitute rthesecond uni-t wand yare v4designed to #cut spaces of the l'fullprescribed-depth and `width,

thus reducing thewidth and l'increasing 4the lengthfofthe incompleteteethrst generated. So Ifaras=thebasic principles ofthe method -areconcerned,:eachofsaidlunlts isa complete cutter.Y

Thatlis,1the teeth t'y maybe of such 'form andfdlmensions -as )to :cutspaces fand vgenerate teeth -of the prescribed fiinal .dimensions The7provision offtwo .diiferent nun/its :fmerely divides .ithe com'-V pleteprocess into :twosuccessive istpsgiIn other words, the first unit orgroup of teeth embodies the essentials of the cutter for the purposes ofgeneric denition.

These cutters are mounted on rotatable cutter spindles designated as c',c2, etc. at the same distance from the center of the work and theircenters are spaced equally apart from one another on a circular arc orcircumference concentric with the work spindle. Where the work piece isa complete gear, the cutter spindles are equally distributed in acomplete circuit around the work; but for cutting gear segments thecutters need not occupy a complete circumference, and may be spaced atany convenient distance apart (properly correlated with the prescribedspacing of the teeth to be out) without requiring the distance betweenthem to be an integral divisor rof 360 of arc. The absence of teeth froma suiiciently large fraction of the circumference of the cuttersdispenses with the necessity of any radial depth feed.V Y

The number of cutters and the number of teeth on each is determined bythe diameter of the work piece and the number of teeth to be cut, butwith a considerable range of variation. For example, six cutters withfour teeth each, as

, here shown, can cut a maximum of twenty-four aoV teeth in the workpiece, but may also cut a smaller number of teeth. The presentillustration shows them arranged to generate twenty-one teeth in acomplete gear. When the number of teeth generated'is less than the sumtotal of all the cutter teeth, the actions of the successive cuttersoverlap one another somewhat. Cutters of different pitch circle radiusmay be substituted for one another on the same spindles, or on alikenumber of spindles suitably spaced from the work spindle toaccommodate such cutters without interference; and the` number of cutterspindles may -be anything within practical limits. That is, this numbershould not be so large as to require cutters vof smaller diameter andlower diametral pitch than can be conveniently and eiliciently made orsatisfactorily used. Y

In general it may be said that the purposes of the invention are bestcarried out by providing as many cutters of-approximately the smallestpracticable pitch radius as ycan be accommodated in a circular seriesaround the work piece without interfering with one another; since by sodoing the number of teeth required to be generated by each cutter isreduced to the minimum and the production of the work expedited to thatextent. But the invention is not limited in that respect, and may beembodied in conditions where the number of cutters is less than themaximum and the number of teeth in each unit is proportionallyincreased. By providing a suitable number of cutters at a suitablecenter distance from the work, with a proper number of teeth on each andproper adjustment of the cutters angularlyy on their respectivespindles, gears can be cut `with any number of teeth equally spacedaround their pitch circumference even though the number of teeth is aprime number.

In the embodiment here described, the pitch circle spacing of the cutterteeth is equal to the pitch circle spacing of the teeth to beproclucedin the work, and the angular spacing of the cutters around the axis ofthe work, and the posi- They are all nection I mean the unit spacingmultiplied by an integer greater than one. The cutters may be secured totheir respective spindles with any angular adjustment. That is, theyneed not be adjusted so as to begin cutting all at the same instant, butmay come into action successively in any sequence necessary to cut anygiven number of teeth with equal spacing. Thus,.for instance, in theillustration shown, the cutters b', b3 and b5 are located so as to begincutting at the same instant and to locate corresponding cuts made byeach at any given instant exactly 120 apart around the axis of the work.But the intermediate cutters b2, b4 and D6 are adjusted with anlangulardisplacement about their axes equal to the spacing of one, tooth,relatively to the previously specied cutters, in order to be propverlycorrelated for cutting twenty-one teeth. For

vcutting other numbers of teeth,rthe cutters may be otherwise adjusted;but in all cases they are so correlated that the teeth which each cuttergenerates are in uniform and equal spacing with the adjoining teeth`produced by the adjacent cutters. o Y

The necessary rolling motion between cutters and work for generatingcorrect tooth forms may be obtained by rotating the cutters about theirrespective axes all at the same speed and in the same direction ofangular rotation, for instance, that indicated by the arrows d', d2, d3,etc., and simultaneously'rotatng the work about its axis in theoppositedirection at the same peripheral speed; or by holding the workstationary and revolving the cutters bodily around the axis of the workin the `direction of the arrow-f, at a speed which causes them to rollwith respect to the work in the manner of planet gears. In theillustration of Figs. l and 2 it is assumed that the work `and'cuttersare rotated in xed locations; Further on in this specification means aredescribed whereby the cutters are both rotated and revolved.

The use Aof cutters with teeth occupying less than their fulllcircumference eliminates necessity -for any-change of center distancebetween cutters yand work for depth feed. This is because the large gapin the circumference of the cutters-where there are no teeth permitsplacement of the work in pitch circle relationship with the cutters, orVice versa, when the blank sides of the cuttersare turned toward thelocation of the work piece, without interference be- -tween` the cutterteeth and the circumference of and t2 in the present illustration, areprovided,v

the teeth of the second series or unit are brought into action bycontinuing the rolling movement through a sufficient additional angle.l'n so doing, the teeth t2 of cutter'b' enlarge the "spaces and reducethe ,width of the teeth of the Work piece cut by the teeth t of cutterb2; and each cutter thus performs a second cutting actionY on the teethgenerated by the i'lrst cutting unit of thepreceding cutter. But it is amatter of choiceawhethertthe.completemuttlngxyclejsaperformed .finfone..j step sor stwci or: more; steps. s Gene'rially:a-.l'better==.'nish isfsobtai'ned `)by :the pluralstepfembodirhentfofitheiprocessithe teethk ofthe second-or -ffinalAuriitgzbeingdesigned :to take :a lightfcut... LV n v .Ifhave shovvninEig: Stof theLdraWing,iin' ,-a:dia grammaticnmay, aan -apparatus ,by.:.Which. :the

" foregoing'methodmay be performed.` .fflIhissapparatus` embodies.ftheprinciples .of :the means which fI fhave .-:devfised for the,fpurpose; :together with -Ifurther 1 developments invented -by ylV.Miller :of iSpringeld, 'vermontg :1in applyingithese principles to .1anf'drganizeds. `commercial machine. Hereilfthe work :piece la, vismounted y'on' wanuiarbor t0 securediinraholder lil which iss'taticnary-While the sgenerating factionitakes fplace; and may be displacedi'forila'pplying' and removing i the work.

'I-heicuttenspindle's lare :rotatably'afrnounted fin a cylindricalcarrier M2 V1fvvl'ii'ch is ":rotatableaand movable .endwise Lin afstationary'bearing [3 l coaxial with-the Workspindle-axis.--*'I'hiscarrier is reciprocatedl'by-y a gear` segment td `:whichImeshes with-encircling.rackteethfl gon the circumference of Athecarrier and -is oscllated -at a i suitablespeed by'mechanismlnotshown.The carrier-lzvisrotatl ed-fto-carry thespindleslin ansorbit around theaxis offthewoifkjby a-Worm'il fmeshingwith a Widefacedigearl'l-Whichiremainslin 4rneshj-vvith the Worm@ throughout 'fthefstroke i of the fca'rr-ier, and isnrigidly secure'diitofthev4oarrier`..l2.y This gearV serves alsocas :a-thrustblook acting throughball t bearings 'il 8 fforapropelling the "cutters e'ndwise Iinlfthecuttingv idirection and i withdrawing them. VRotationH-of ftl'iefcutters:about their 1individual axesat :thei proper =speediis :causedby f-a ygear I9, normally yheld stationary, iwithf-.Which meshcgears .2U Yon therespective .cutterfspindles TheA gears 'F20 slide lengthwise rin` meshwithsgear |:9 fasfthegcuttersv are reciprocated, :and ythe. inter.-

eng-aging :teeth :of ftherse. gears guide'the cutter vteeth :in their'.true' paths ynecessary "for shaping the teethof the-Work.'Whenzhelicalteethuare to .be generated, icutters are .used otzwhich theteeth :are'li'elical lin the x prescribed fdegreey' and the gears i9 and2i! arey helical gears-'ofrthefsame lead as the ,cutter'teeth To eiect.vbacking'oiof :the cutters =suflicient `4to Vavoid `cub on their:return strokes, the

spindles :are formed Iwith tapered portions '12| near :the @end Vonvwhich A'the rcutters .lare mounted, which jt vcornplementally v.tapered`@bores in vvsleeves :"22 :whichrinturn'have rotative bearing in a',head 2:3 :tted Yfin f the adjacent gend :.of 1 the carrier :1:2 with.lprovisionfor '.-endWi-se, i movement l i-e1ativelnthereto,;but insplinediconnectiontherewith to prevent iiindependentrotation. SpringsMireactbetweenrthe spindle carrierfan'd headz23 ycu ' and cuttersradially outward to the-,distance permitted by the displacement ofthesleeve The ball' thrust bearings |'8,-being ata longidistance 'frcmthecutters;v permit such displacement` ofthe cutters :to .the small extentLwhich `is Ysufcientior tinuous series fof-teeth.

this purpose .i "Whenfthespindlesaare-jalear :di .fthewcrkratzthezfendof theirfy return strokesgthetgear 2l pullsathe rod;outward`-and therebyabrings-rthe tapered 'sleevesfagain fintofcloseengagement the Vspindle,:returning the cutterstto :cutting zpnsi.-

tion. fElseiwhere throughout'the flength -ff the spindles there isssuficient clearance "ehetweenfthe spindles andcarriertofzpermitt-hisfoutward .move- .nerit;. i

. am Vaware that the simultaneous .generation Vcf f a number of zgearsV:by: a'ssing'le 1 cutter is not new. isFcrpinstance, rthe :patentofifiEdward Millen; No." 113990240, dated February 35, hv193.5,vshowszthe useoffan'interruptedycutter'with tazgplurality ci liseri'es@of *teeth lof aprogressivelyelarger And the patent to G. FornacaleiNo..1;6U4-,984, November xl92`6, :showsathree :work-'spindles -sur-`pounding,v ;and Y acted tupon :simultaneously tby; -a

largeilcutter l:havingiaseries. lof f identicalrteethiucupyingfitsaentire circumference. gauhmyfmethoddiffersifundamentallyffrom' both of,;these1patents in havinga.1;.plurality o'f fouttersf;a11^.pperafting simultaneously:.onfonegear, and `eachsgenerating f A teethaim onlyja AEmotional part'of :the :circumference of the gear. :Tofthe'rbestof myifknowledge andibelief, fthis Lrnetl'iod is-,wholly-new ;Itlhas a number @of :importantadvantages .'over-the'zprior methods fin :that it permits :the fuse :notsonlyzot v cutters 4'ofsthe :dimensions long .fpreviously:conside'redrassstandard, fbut-:cuttersi which? have .onlyatsmallfraction ofitheznurr'iber,A of'steethfreverrhereof fcuttermanufacturing cost. 'Then 'thefsize of gearsWhichsmayrbezzthusgeneratedfis practicallyV unlimitednand cuttersvaryingWithin'onlyfa small range ;of'tradial dimensions .may abe used :toproduce gears iofxzanyrrandzrzall dimensionsyfin `fo'f course a smallfractionr of ttlre time-regu1nedrto produce fany :such -gear withsa'rsingle cutter. Again, the .rapidity of s production :due toamultlple simultaneous action 'lis obtainablezwithiaieutting assemblagertivorfkholder,:cutter sspindlfestand-'cooperating :partslfiof compact:proportions:

sists in -fpr'ovidingsa Iplurality-of =g`ear xshaperacutters around thecircumference of 'ethesworkgpleca ineall of f which the n`teeth Pareequally Laird:- un.- formly spaced, locating the cutters "to: fact,-fsim'ultaneously iat-'points --spaced apart 4on fsuch ciroumferenoe lby vfan `integral 1 multiple 'of fthefprescribed toothspacing,and-effectingsimultaneous relative cutting reciprocation"'andirollingimotion between "the f cutters dand i work piece Yuntil wtheteeth generated by thefseveral Y cutters'ffeach-iin fa limited sector cf 'fthe work '-pieee; arcan-v Y 2. y"Ihedrne'thod -o'f generating/1gearsfwl'iich non# vsists in #cutting 'teeth simultaneously inAdifferent portions of the'circumference-ofv-afsinglerwork piece'by-gear `VShaper cutters A:all of Which l-have' teeth Elike "one vancther"irl-fcrm and spacing nand Which-arefsoicorrelatedfto oneanotherandrtothe Workthat @the ycuts "simultaneously "marde 'by *cor-1responding teeth of the respective cutters are spaced :apart L'ori *the--oircumferen'ce "off the -work piecefby-a distance-equalfto'theprescrib'edtooth spacingY 'of f'the fwoi'k piecey multiplied byaniinteger greater than one; Vand effecting relative cutting and rollingVmotions."betvveen" the Vcuttersf'andtlie workpiece'. Y 'f :3. .lIh'eimethod of. .gear tgenerationlwhi'ch icon- *miA I6 dimensions tto.lcooperatefzwith @Work fpiecesncarv ried hyf 'spindlesnina aplanetatyarrangement.

sists in operating simultaneously on a single gear blank by means of aplurality of cutters of the gear Shaper type, each having a number ofteeth sufficient to generate a fraction of the whole number of teeth tobe cut in the work.

4. The method of gear generation which consists in providing a pluralityof segmental gear Shaper cutters equally spaced apart from one anotherln a circular arc concentric with the axis of the gear being out,simultaneously effecting relative cutting traverse between said cuttersand the Work piece in the direction of the axes of the cutters, andsimultaneously effecting relative rolling motion between the work pieceand cutters through an angle suflcient to bring a subsequently actingtooth of a given cutter into the space cut by a precedently acting toothof the next preceding cutter.

5. The method of gear generation which consists in simultaneouslycutting and generating a plurality of teeth by individual cutters indifferent parts of the circumference of a workpiece, separated from oneanother by a distance greater than the prescribed tooth spacing, andcontinuing the tooth generation until intermediate teeth are made,formingV with those first out a complete uninterrupted series of teeth.

6. The method of gear generation which consists in providing a number ofgear Shaper cutters in a planetary arrangement around a single workpiece, effecting relative axial reciprocating movements between the workpiece and all of said cutters in unison, correlating the cutters withone another so that the grooves cut by each are at a distance apart fromone another equal to a prescribed multiple of the spacing of the teethto be generated in the Work, and effecting relative angular movementabout their respective axes of the cutters and work like that oi! gearsrolling in mesh with one another.

7j. TheY method of gear generation which con sists in simultaneouslycutting a fraction of the whole prescribed number of teeth by individualgear Shaper cutters in diierent parts of the cir-` cumference of aworkpiece, and continuing the tooth generation, with relative rollingmotion between the cutters and work, until a subsequently acting toothof each cutter enters the tooth-space generated by the first actingtooth of the next preceding cutter.

8. The method of gear generation which consists in providing a number ofgear Shaper cutters each having teeth equally spaced throughout afraction only of its circumference and substantially identical withcorresponding teeth of the other cutters, placing said cutters at equalcenter distances from a gear blank in circular series around the axis ofthe blank, adjusting the cutters about their respective axes so thattheir toothless Sides are next to the blank and so that their respectivefirst cuts made in the generating action will be spaced apart on thecircumference of the blank by an integral multiple of the predeterminedtooth spacing, and electing simultaneous axial reciprocative cuttingmovements and relative rolling movements like those of gears running inmesh between the blank and all of the cutters. Y

9. The method of gear generation which comprises locating a series ofcutters with equal angular spacing around a gear blank at equal centerdistances from the axis of the blank, such cutters having radial teethwith outing edges at one end, the circular pitch of which is equal tothe circular pitchof the teeth designed to be generated, and

the number of which on each cutter 1S at least as great as the number ofteeth required to be cut in the sector of the work bounded by the radiiof the blank on which the centers of such cutter and of the nextadjacent cutter respectively are located, adjusting the cutters abouttheir respective axes so that the first tooth of each to come intocutting action will incise the blank at a point distant from the outmade by the rst acting tooth of the next adjacent cutter equal to anintegral multiple of the prescribed tooth spacing, effecting a relativemotion of axial reciprocation between the blank and cutters for cuttingthe work with a shaping action, and simultaneously eiecting relativerotation between the cutters and blank'about their respective axes inthe manner of gears running'in mesh together.

10. The method of gear generation which comprises mounting a pluralityof cutting tools around the axis of a gear blank in position to cutsimultaneously at different points in the circumference of the blank andwith an angular spacing from one another greater than the angularspacing of the teeth to be cut, effecting repeated relative movementsbetween the gear blank and all of the tools lengthwise of said axis rstin one direction and then in the opposite direction to such extent thatgrooves are cut in the blank from one end toward the other by the tools,and effecting relative lateral movements between the blank and tools atsuch a slow rate with respect to the rate cfsaid lengthwise movements asto cause each tool in the course of a multiplicity of said lengthwisemovements to cut a plurality of grooves and to shape the materialbetween such grooves into gear teeth of predetermined outline.

1l. The method of spur and helical gear generation Which consists insimultaneously cutting grooves in different sides of a cylindrical gearblank Separated from one another by an angular spacing greater than thatprescribed between adjacent finished teeth of the gear to be cut,throughout the length of the blank, thereafter simultaneously cuttingother grooves one after another in sectors of the gear blank between thegrooves rst cut.

l2. The method of gear generation which consists in cutting a number ofgrooves simultaneously in different sides of a gear blank by a likenumber of different tools spaced equidistantly from the geometrical axisof such blank and angularly around such axis with a spacing greater thanthe prescribed angular spacing of the teeth to be cut, progressivelycutting other grooves by each tool simultaneously in different Sectorsof the blank'between the grooves first cut, and causing the severaltools each to generate to nal finished dimensions and outlines, as toothSpaces conjugate to the teeth of a mating gear, the grooves cutpreviously by another tool.

13. A gear generating apparatus comprising a Series of cutter spindlessupported in circular arrangement about, and with their axes parallel toand equidistant from, a central axial line, a work holder having meansfor supporting a gear blank with the center of its rim in which teethare to be out coincident with said central line, means for eiectingrelative rotation between the work holder and cutter spindlessimultaneously around said central line and the axes of the severalspindles, and means for effecting relative reciprocating movementsbetween the Work holder and cutter spindles in the direction of saidcentral line.

14. A gear generating apparatus comprising a plurality of cutters eachhaving peripheral teeth vrotatable and axially reciprocable cutterspindle of similar outline to gear teeth extending through less than itsentire circumference, means for supporting said cutters' equidistanlyspaced from a central point with their toothless sides facingYtowardsuch point, a work holder having means a for mountingv a gearblank with its axis in coincidence with said central point, means foreffect- 'ing relative reciprocation between the work holder and all thecutters lengthwise of such axis, and means for relatively rotating thecutters and work holder around said axisv and simultaneously rotatingthe several cutters Varound their own axes.

15. A gear generating apparatus comprising a plurality of cutters eachhaving peripheral teeth of similar outline to gear teeth extendingthrough less than its entire circumference, means for supporting saidcutters equidistantly spaced' from Va central point with their toothlesssides facing toward such point, a work holder having means for mountinga gear blank with its axis in vcoincidence with. said central point,means for revolving the cutters around said axis and simultaneouslyrotating them individually around their own axes, and means foreffecting relative reciprocation betweenlthe cutters and work holder inthe direction of said axis.

16. A gear generating apparatus comprising a 'plurality' of cutters eachhavingperipheral teeth of similar outline to gear teeth extendingthrough less than its entire circumference, means for supporting saidcutters equidistantly spaced from a central point with their toothlesssides facing toward such point, a Work holder having means for mountinga gear blank with its axis in coincidence with said central point, meansfor revolving the cutters around said. axis and simultaneously rotatingthem individually around their own axes, and means for reciprocating thecutters relatively to the work piece inA paths such that their teeth/are caused torgenerate teeth in the work piece.

1'7. A gear generating apparatus comprising a rotatable and axiallyreciprocable cutter spindle carrier, a plurality of spindles rotatablymounted in said carrier equidistant from the axis of rotation thereof, aWork holder having means for holding a gear blank in alinementvwith saidaxis, means for rotating saidspindle carrier and simultaneously rotatingthe spindles about their respective axes,4 and means for reciprocatingthe spindle carrier. Y

18. A gear generating apparatus comprising a carrier, a plurality .ofspindles rotatablymounted in said carrier equidistant from the axis ofrotation thereof, each protruding at one end from one and Athe same endof Ythe carrier, a work holder having means for holding argear blankadjacent to the end Aof the carrier from which the spindles protrude andin axial alinement with said axis, cutters mounted on the protrudingends Vof the spindles in a location to be carried back and forth byreciprocation of the carrier across the rim of a gear blank so located,means for reciprocating the carrier, and means for rotating the carrier,and simultaneously rotating the spindles about their own axes. J

19.Y A gear generating apparatus comprising a rotatable and axiallyreciprocablecutter spindle carrier, a plurality of spindles rotatablymounted in saidcarrier equidistant from the axis of rotation thereof,each protruding at one end from oneV and the same end of the carrier,cutters mounted on the protruding endsof the spindles, each hav- -ingperipheral teeth of outline similar to gear teeth throughout a fractiononly of their pe- I ripheries, a work holder having means for holding agearv blank with its rim in a location between the limit ofreciprocation of the cutters and Within the orbit of the cutters, meansfor reciprocating the carrier, and means for rotating the vcarrier aboutsaid axis and simultaneously rotating the spindles about theirrespective axes.

20. A gear generating apparatus comprising a l rotatable and axiallyreciprocable cutter spindle carrier, a plurality of spindles rotatablymounted in said carrier equidistant from the axis of rotation thereof,each protruding at one end fromv one and the same end of the carrier,cutters mounted on the protruding ends of the spindles, each havingperipheral teeth of outline similar to gear teeth throughout a fractiononly of their peripheries connected to their respective spindles sothat, in one position of the assemblage, Vthe toothless sectors of allface toward said axis, a Y' work holder having means for holding a gearblank with its rim in a location between the limits Y of reciprocationof the cutters and .within the orbit of the cutters, means forreciprocating the carrier, and means for rotating the carrier about saidaxis and simultaneously-rotating the spindles about their respectiveaxes.

EVERARD sTUBBs.

